Question

this is a code sample:

class md {
public function __construct() {
    if($this->getIsGuest()){
        echo 'iam guest';
    }
}
public function getIsGuest() {
    return $this->getState('__id')===null;
}
public function getState($val) {
    return '3';
}

is return $this->foo() === null is the default value of foo of nothing returned ?

Answer 1

getIsGuest() is returning the comparison of $this->getState(‘__id’) to null.

If $this->getState('__id') returns exactly null, then getIsGuest() function returns true. If it returns anything except exactly null, then the getIsGuest() function returns false.